The Caledonia Fire Department said 19 cars of a Union Pacific train went off the tracks.

Authorities said no one was hurt, and there were no concerns about hazardous materials.

Some witnesses said they didn't hear anything that sounded like a derailment.

"Just train cars piled up on top of each other, axles on the side of the tracks and rails sticking up in the air," said 11-year-old witness Nicholas Olley.

"Quite a few train cars that are off the track, tipped over, looks like coal, lot of dumped coal on the ground," said Robert Grove, a supervisor on the Racine County Board.

Wisconsin Railroad Commissioner Jeff Plale said the derailment may have been related to the weather.

“Right past the bridge, they hit some broken track and when you have really cold weather like this, tracks can get, steel can get brittle and the extreme temperatures are tough on the railroad,” Plale said.

“If it gets too hot, steel expands and you can get heat kinks, and when it gets really cold, just the tiniest fissure in the steel can get brittle and snap."

Plale also said crews will work through the night to clean up the scene and trains should be running in the area soon.

The train was carrying coal to the Edgewater Generating Station, a coal-fired electric plant in Sheboygan. Alliant Energy said they get three train loads a week, and have plenty on-site, so there's no immediate problem.